/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.jasper.util;

import org.apache.jasper.compiler.Localizer;
import org.xml.sax.Attributes;
import org.xml.sax.helpers.AttributesImpl;

import java.util.HashSet;
import java.util.Set;

/**
 * Wraps the default attributes implementation and ensures that each attribute
 * has a unique qname as required by the JSP specification.
 */
public class UniqueAttributesImpl extends AttributesImpl {

	private static final String IMPORT = "import";
	private static final String PAGE_ENCODING = "pageEncoding";

	private final boolean pageDirective;
	private final Set<String> qNames = new HashSet<String>();

	public UniqueAttributesImpl() {
		this.pageDirective = false;
	}

	public UniqueAttributesImpl(boolean pageDirective) {
		this.pageDirective = pageDirective;
	}

	@Override
	public void clear() {
		qNames.clear();
		super.clear();
	}

	@Override
	public void setAttributes(Attributes atts) {
		for (int i = 0; i < atts.getLength(); i++) {
			if (!qNames.add(atts.getQName(i))) {
				handleDuplicate(atts.getQName(i), atts.getValue(i));
			}
		}
		super.setAttributes(atts);
	}

	@Override
	public void addAttribute(String uri, String localName, String qName,
	                         String type, String value) {
		if (qNames.add(qName)) {
			super.addAttribute(uri, localName, qName, type, value);
		} else {
			handleDuplicate(qName, value);
		}
	}

	@Override
	public void setAttribute(int index, String uri, String localName,
	                         String qName, String type, String value) {
		qNames.remove(super.getQName(index));
		if (qNames.add(qName)) {
			super.setAttribute(index, uri, localName, qName, type, value);
		} else {
			handleDuplicate(qName, value);
		}
	}

	@Override
	public void removeAttribute(int index) {
		qNames.remove(super.getQName(index));
		super.removeAttribute(index);
	}

	@Override
	public void setQName(int index, String qName) {
		qNames.remove(super.getQName(index));
		super.setQName(index, qName);
	}

	private void handleDuplicate(String qName, String value) {
		if (pageDirective) {
			if (IMPORT.equalsIgnoreCase(qName)) {
				// Always merge imports
				int i = super.getIndex(IMPORT);
				String v = super.getValue(i);
				super.setValue(i, v + "," + value);
				return;
			} else if (PAGE_ENCODING.equalsIgnoreCase(qName)) {
				// Page encoding can only occur once per file so a second
				// attribute - even one with a duplicate value - is an error
			} else {
				// Other attributes can be repeated if and only if the values
				// are identical
				String v = super.getValue(qName);
				if (v.equals(value)) {
					return;
				}
			}
		}

		// Ordinary tag attributes can't be repeated, even with identical values
		throw new IllegalArgumentException(
				Localizer.getMessage("jsp.error.duplicateqname", qName));
	}
}
